Hand held electronic thermometers offer many advantages over glass-tube mercury thermometers. In the basic electronic thermometer design, a temperature sensing element is connected to a combined, battery-powered computing and display element. These components are housed in a rigid plastic case having a probe with handle shape. The temperature sensing element is mounted at the end of the probe section and covered with a metal cap. The computing and display element as well as the battery are secured in the handle section of the rigid case, where a viewing window is provided for the temperature display and an access door is provided for the battery. The components are interconnected by wires or leads.
Although such thermometers have enjoyed wide-spread commercial acceptance since the 1970s, efforts at improvement on this basic design continued. To date, numerous advancements have been made. These advancements include mouth-friendly flexible probes, fast-response sensing elements, and audible signaling.
Concerning improvements in probe flexibility for example, U.S. Pat. No. Des. 254,189 to Prosky illustrates a relatively early design of an electronic thermometer with a flexible probe. Giving a somewhat later design, U.S. Pat. No. 5,165,798 to Watanabe also depicts a hand-held electronic thermometer with a flexible probe.
Efforts at improving measurement response times are reflected in U.S. Pat. No. 4,688,949 to Hatakenaka. This patent is directed to a customized multi-layer temperature sensor designed for use in a hand-held thermometer. Infrared-based thermometers having ear probes have also been developed in an effort to further reduce response time. See for example, U.S. Pat. No. 4,993,424 to Suszynski et al.
While offering desirable features, these "improved" thermometers all suffer at least one serious drawback: they are very expensive to fabricate.
The flexible-probe feature, in particular, adds greatly to the costs of production. As U.S. Pat. No. 5,165,798 to Watanabe well demonstrates, the conventional flexible design is multi-piece and multi-layer, requiring a flexible tube mounted to a rigid case with an elastomeric cover surrounding the tube and cover.
So far, faster response times have also come only at greater expense in production. One of many available examples, the fabrication process described for the fast-response probes of U.S. Pat. No. 4,688,949 to Hatakenaka is a multi-step recipe including multiple high temperature baking steps and a laser trimming step. And while said to be fast in their response, the infrared ear probe thermometers are well known to be not only more expensive to make but also less accurate.
To be commercially successful, medical devices designed for the price-sensitive consumer market must be advanced in features but still inexpensive to fabricate. Accordingly it would be desirable to provide an improved hand-held electronic thermometer having a cost-effective design. Specifically, it would be desirable to provide the advantages of the more-expensive flexible probe and fast-response designs without the excessive fabrication costs.